For sysadmins

To install in /usr/local/{include,lib,bin,man}:

./configure && make -j8 install

For developers with an unprivileged account

Typically you'll already have

export LD_LIBRARY_PATH="$HOME/lib"
export LIBRARY_PATH="$HOME/lib"
export CPATH="$HOME/include"
export PATH="$HOME/bin:$PATH"

in $HOME/.profile. To install in $HOME/{include,lib,bin,man}:

./configure --prefix=$HOME && make -j8 install

For distributors creating a package


./configure --prefix=/usr && make -j8

and then follow your usual packaging procedures for the build/0/package files:


The libcpucycles and librandombytes packages are build-time and run-time prerequisites; the python3 and compiler packages are only build-time prerequisites.

More options

Before ./configure you can run ./use-s2n-bignum to download various .S files from s2n-bignum and integrate them into lib25519. The critical feature of these .S files is that they are formally verified to work correctly on all inputs. The files cover, for 64-bit Intel/AMD/ARM, the main nG and nP subroutines used in X25519 key generation and shared-secret generation; the files also save some time on some of these CPUs, although not all. If you want to disable the other nG and nP implementations, you can run chmod +t crypto_{nP,nG}/montgomery25519/* before running ./use-s2n-bignum.

You can run

./configure --host=amd64

to override ./configure's guess of the architecture that it should compile for. The architecture controls which implementations to try (see crypto_*/*/*/architectures) and which compilers to try (see compilers/*).

Inside the build directory, 0 is symlinked to amd64 for --host=amd64. Running make clean removes build/amd64. Re-running ./configure automatically starts with make clean.

A subsequent ./configure --host=arm64 will create build/arm64 and symlink 0 -> arm64, without touching an existing build/amd64. However, cross-compilers aren't yet selected automatically.

Version: This is version 2024.02.25 of the "Install" web page.